A mobile device includes a connector, an audio generator, a biological signal processor, a switch element, and a controller. The switch element has a first terminal and a second terminal. The first terminal of the switch element is coupled to the connector, and the second terminal of the switch element is selectively coupled to either the audio generator or the biological signal processor according to a control signal. The controller is coupled to the audio generator and the biological signal processor, and is configured to generate the control signal.