Systems are disclosed for the combined measurement of linear and angular displacements, with high sensitivity, wide measurement band at low frequency based on the configuration of the folded pendulum, and a linear and angular displacement sensor for applications of monitoring and control. Examples of possible applications of the combined sensor subject-matter of the present invention are sensor for the seismic monitoring, sensor for systems of monitoring and/or control of civil and industrial buildings, dykes, bridges, tunnels, etc., sensor for system of monitoring and/or control for the realization of systems of seismic attenuation and inertial platforms.