A force sensor (50, 50', 50a) generates a signal indicating the usage of a seat belt. A cylindrical housing (70, 70') has a wall (72) and a bottom (74) which define an internal cavity (88). The bottom has an opening (76) through it. A cable anchor (90) is slidably received within the cavity and is connected to a cable (54). The cable has one end secured to the cable anchor and another end connected to an anchor point. A magnet (120) is connected to a top of the cable anchor and is movable with the cable anchor. The cable anchor is biased to resist motion of the cable anchor toward the bottom of the housing. A magnetic sensor (200) generates a signal indicative of the distance between it and the magnet. A sensor housing (180) is connected to the housing and is positioned on the housing to position the magnetic sensor a determinable distance from the magnet at a null position. A housing end cap (150) is secured to the housing for enclosing an open end of the housing. The magnet and the magnetic sensor are movable when a force of a determinable level is applied to the end cap causing the relative movement of the magnet and the magnetic sensor.