A:
On your surface pro 4, go to
1. Settings.
2. Bluetooth and other devices
3. Under Bluetooth, slide the button to "ON"
4. At the top, under "Add Bluetooth and Devices," click on the plus sign.
5. Choose the "Bluetooth" devices. At this point it will try to discover.
6. Follow the steps on this link: http://support.logitech.com/en_us/article/26700?product=a0qi00000069v00AAA
7. It should discover it as "H800 Logitech Headset"
8. Click on to pair it.
9. Once it is paired, on the same setting screen, under "Audio" you should see the logitech h800 headst.
Hope that helps. Keep the USB dongle in the headphone so you will not loose it.