Get-ChildItem -Path C:\Diskpart.exe -Recurse
But that gives you Access Errors and also ALL occurences of Diskpart
Ofc you could just do something like
Get-ChildItem -Path $Env:Windir\Diskpart.exe -Recurse
to make sure it's at least in the win directory. It SHOULD always be in system32 though
Get-ChildItem -Path $Env:Windir\System32\Diskpart.exe
but assuming this makes the file search obviously unnecessary