How to use a bluetooth mouse in Gear VR?

we have the problem that we have no idea how to get the input data of a connected bluetooth mouse in unity.
The mouse is working fine since we see the cursor in Android OS. But we can not backtrack how this input is mapped in unity,

Thank you.

What I know is that I can use this Bluetooth mouse in the Samsung VR Browser. You simply connect the mouse and use it as an alternative for moving the pointer. That’s why I “know” or at least hope, that there is the possibility of using this mouse as an optical sensor in any VR application.