System and method for detecting an input for an apparatus inside a vehicle, wherein at least one moving user device generates a changing electromagnetic field. A detection unit detects at least one field parameter of the electromagnetic field, wherein the detected field parameter is a function of the geometric arrangement of the user device relative to the detection unit. A radio signature of the user device is determined based on the detected field parameters, and a signature sequence is determined based on a sequence of time-sequentially determined radio signatures of the user device. The determined signature sequence is then assigned to an input gesture, and whereby, based on the input gesture, a signal is generated and output.