A modular magnetostrictive displacement sensor is disclosed having a waveguide of magnetostrictive material extending from a first housing and protected by a member of fiber reinforced composite material. There is circuitry in the first housing for generating electrical pulses along the waveguide and a converter for generating an electrical signal in response to a torsion pulse in the waveguide caused by a magnet disposed proximate the waveguide when the electrical pulse passes the magnet position. In one embodiment the waveguide and its protective member is received within a second housing. One or more magnets may be mounted within the second housing or externally on or near the second housing for movement to the waveguide. Alternatively the sensor may be used without the second housing.