A sensor system is provided. The sensor system includes a control device and a sensor device. The control device has an audio combo jack and selectively provides an audio signal to the audio combo jack. The sensor device is connected with the audio combo jack. The sensor device includes a transformer, a rectifier, a power supply circuit, and a sensor. The transformer receives the audio signal through the audio combo jack and amplifies the audio signal to generate an amplified audio signal. The rectifier, coupled to the transformer, receives the amplified audio signal and rectifies the amplified audio signal to generate a rectified voltage signal. The power supply circuit is controlled by the rectified voltage signal to provide a supply voltage. The sensor is powered by the supply voltage to perform a sensing operation. An output signal which carries information related the sensing operation is generated.