The synchronous sampling scanning force microscope includes a reflective cantilever arm having a free end which is oscillated at a frequency different from the resonance frequency of the cantilever arm. The motion of the oscillating cantilever arm is measured, to generate a deflection signal indicative of the amplitude of deflection or phase shift of the cantilever arm. Selected portions of cycles of the output signal are sampled, for generating output signal data indicative of deflection of the near and far excursions of the probe. The method and apparatus permit monitoring of compliance of the surface of the specimen by multiple sampling at a rate greater than the period of oscillation of the cantilever probe of the microscope.