//using System.Management
public bool IsUsbDeviceConnected(string pid, string vid)
{
  using (var searcher =
    new ManagementObjectSearcher(@"Select * From Win32_USBControllerDevice"))
  {
    using (var collection = searcher.Get())
    {
      foreach (var device in collection)
      {
        var usbDevice = Convert.ToString(device);

        if (usbDevice.Contains(pid) && usbDevice.Contains(vid))
          return true;
      }
    }
  }
  return false;
}