A whispering gallery mode inertial sensor includes a whispering gallery mode resonator; an evanescent coupler configured to couple with an evanescent field of the resonator so that light is transmitted to and received from the resonator by the coupler; a displacement sensor configured to determine a displacement of the resonator according to the light received from the resonator by the coupler; a controller configured to determine an acceleration and/or rate of rotations experienced by the resonator based on the displacement of the resonator, the controller being further configured to apply a restoring force to the resonator in a closed feedback loop based on the displacement of the resonator in order to maintain a predetermined mechanical state of the resonator; and a timing sensor configured to determine a timing signal based on an optical frequency comb produced by the resonator.