Use the property PSParentPath
:
$key = 'SOFTWARE\Microsoft\Windows\CurrentVersion\MMDevices\Audio\Capture'
$pathToIntMic = Get-ItemProperty "HKLM:\$key" | ? { $_.Name -eq "internal mic" }
Write-Host $pathToIntMic.PSParentPath
You can enumerate the properties and methods of an object by piping it into the Get-Member
cmdlet:
$pathToIntMic | Get-Member