I was recently asked to figure out a way to determine which users had cache mode enabled in Outlook 2016 and the end result is the script below.

In order to run the script, you will need to specify the following variables:
$Directory = Insert the exact path of where you would like to save your report ( EX: C:\Reports)
$File = Insert the file name of your report (EX: MyReport.csv)
$ComputerList = Insert the full path of your computer list (EX: C:\Computerlist.txt)


<#  

.SYNOPSIS  
    Run a report to find who is in Outlook Cache Mode

.NOTES  
    File Name  : OutlookCachingReport.ps1  
    Author     : Jose Espitia
    Requires   : PowerShell V5
    Version    : Version 1.00

#>

# Specify where to save the report
$Directory = "C:\Reports"
$File = "MyReport.csv"

# Computer list
$ComputerList = "C:\ComputerList"
$Computers = Get-Content "$ComputerList"

ForEach($Computer in $Computers) {
    
    Try { 
        # Test connection with computer
        Test-Connection -ComputerName $Computer -ErrorAction Stop
        # Query remote machines
        $HKEY_Users = [Microsoft.Win32.RegistryKey]::OpenRemoteBaseKey("Users",$Computer)
        # Get list of SIDs
        $SIDs = $HKEY_Users.GetSubKeyNames() | Where-Object { ($_ -like "S-1-5-21*") -and ($_ -notlike "*_Classes") }

        # Associate SID with Username
        $TotalSIDs = ForEach ($SID in $SIDS) {
            Try {
                $SID = [system.security.principal.securityidentIfier]$SID
                $user = $SID.Translate([System.Security.Principal.NTAccount])
                New-Object PSObject -Property @{
                    Name = $User.value
                    SID = $SID.value
                }                 
            } 
            Catch {
                Write-Warning ("Unable to translate {0}.`n{1}" -f $UserName,$_.Exception.Message)
            }
        }
        $UserList = $TotalSIDs 

        # Loop through users to determine If they are in cache mode
        ForEach($User in $UserList) {
            # Get SID
            $UserSID = $User.SID
    
            # Get list of Outlook profiles
            $OutlookProfiles = $HKEY_Users.OpenSubKey("$UserSID\SOFTWARE\Microsoft\Office\16.0\Outlook\Profiles\Outlook\")
    
            # Loop through Outlook profiles to find caching key
            ForEach($Profile in ($OutlookProfiles.GetSubKeyNames())) {
        
                $ProfileKey = $HKEY_Users.OpenSubKey("$UserSID\SOFTWARE\Microsoft\Office\16.0\Outlook\Profiles\Outlook\$Profile")
        
                # Locate cache key
                If(($ProfileKey.GetValueNames() -contains "00036601") -eq $True) {
                    $Result = $ProfileKey.GetValue("00036601")
                    # Convert value to HEX
                    $Result = [System.BitConverter]::ToString($Result)
            
                    # Determine if cache mode is enabled
                    If($Result -like "8*") {
                        $CacheMode = "Enabled"
                    }
                    Else {
                        $CacheMode = "Disabled"
                    }
                    # Create custom table
                    $Table = New-Object PSObject -Property @{
                        Username = $User.Name
                        SID = $User.SID
                        "Computer Name" = $Computer
                        "Cache Mode" = $CacheMode
                        "Registry Key Value" = $Result

                    } | Select-Object Username, SID, "Computer Name", "Cache mode", "Registry Key Value"
                    # Export table to CSV
                    $Table | Export-Csv -NoTypeInformation -Append -Path "$directory\$file"
                }
            
            }
        }
    }
    Catch {
        # Create custom table
        $Table = New-Object PSObject -Property @{
            Username = "N/A"
            SID = "N/A"
            "Computer Name" = $Computer
            "Cache Mode" = "N/A"
            "Registry Key Value" = "N/A"

        } | Select-Object Username, SID, "Computer Name", "Cache mode", "Registry Key Value"
        # Export table to CSV
        $Table | Export-Csv -NoTypeInformation -Append -Path "$directory\$file"
    }
}

Feel free to leave questions in the comments!