Thanks for this quick response!
Ok, setting the vorpX option “handle gamepad internally” and disabling the controller in the ingame menu brings headtracking to run. Thank you!
Up to now I was not able to map the right keys to the gamepad. I´m not able to change any key bindings in vorpX´s gamepad menu. I tried to klick the respective buttons and pressed the associated button at the gamepad but nothing seems to happen. Have I overlooked something?