In some examples, the apparatus comprises a mechanical input mechanism comprising a rotatable shaft, an optical sensor configured to detect a rotation of the shaft and detect a movement of the shaft toward or away from the optical sensor, and an optical sensor configured to detect light incident on the optical sensor, the light having a position and an orientation, the orientation of the light based on at least a position of the rotatable shaft, detect a rotation of the shaft, and detect a movement of the shaft based on at least a change in the orientation of the light. In some examples, a mechanical input mechanism is coupled to a housing and configured to contact a force sensor coupled to the housing in response to a user input. In some examples, the force sensor is configured to detect a position of the shaft and detect an amount of force between the shaft and the force sensor.