An apparatus may include: a stationary module; a movable module having an outer surface and a substrate; a tactile switch secured on a first side of the substrate; a light indicator secured on a second side of the substrate, the first side and the second side being opposing sides of the substrate, etc. The movable module is configured to generate a spatial displacement relative to the stationary module along a spatial direction in response to a physical force exerted on the outer surface along the spatial direction.