A compact battery-free event detector having a switching element, which can be remagnetized in a bistable manner by a magnet in a sensor coil which then provides an event pulse and supplies a non-volatile memory circuit with a downstream non-volatile display, is designed to detect recurring movements by virtue of the switching element being able to be moved back and forth relative to the magnet between the activation and regeneration fields of its two poles. The manual operation of an inhalation or injection piston in a medicament dispenser can therefore be detected, in particular, and a dose of medicament, for instance, can be monitored thereby. The display is preferably created using e-paper or e-ink technology which, like the memory circuit which is operated only sporadically, obtains its energy needed to change the indication from the event pulse from the sensor coil.