In one embodiment, a system comprises a circuit arrangement and a module having a first mechanical switch and an electrode. The circuit arrangement has a terminal that is connected to the module, a drive unit that is connected to the terminal and serves to provide a drive signal, a first evaluation unit that is connected to the terminal and serves for key detection, as well as a second evaluation unit that is connected to the first evaluation unit and serves for proximity detection. Therein the drive signal is designed for driving an electrode of a capacitive proximity sensor in the module, the first evaluation unit is designed to provide a touch signal according to an actuation of the module by a person, and the second evaluation unit is designed to provide a proximity signal according to an approach of a person to the module.