We study the influence of thermal noise on the rack and pinion coupled by the lateral Casimir force. The pinion position versus time exhibits a sequence of spikes. We identify the Casimir machine as an excitable system equivalent to the Adler system. We show that the interspike time distribution can be analyzed to access the Casimir and friction forces. The inherent susceptibility of nanomachines to the thermal noise can be utilized to measure weak Casimir forces.