$x = "yeah"

$sb = {
  param($n)
  '{0}: {1}' -f $n, $using:x
  $y = 'foo'
  Invoke-Command -ComputerName PC  -ScriptBlock { 'invoke2: {0}' -f $using:y }
}

Start-Job -ScriptBlock $sb -ArgumentList 'job' | Receive-Job -Wait -AutoRemoveJob