3Dconnexion's SpaceMouse Pro and SpaceMouse Compact controllers use a knob called a "controller cap" which provides the 3D navigation by flexing in all directions. When you use the device with VRSG, moving the cap left or right pans in those directions, pulling and pushing pans up and down, moving toward or away from you zooms in and out, and rotating or tilting the cap spins about its various axes. With six degrees of freedom, you can flex the cap in all directions.
The SpaceMouse Pro device has multiple buttons that map to six functions in VRSG.
3Dconnexion SpaceMouse Pro 6DOF controller.
3Dconnexion SpaceMouse Compact 6DOF controller.