An FMCW radar is used to sense an object. A sensor device that senses an object by using an FMCW radar is provided. The sensor device includes: a signal processing unit that acquires a reception signal that is based on a reception wave of the FMCW radar, and senses the object; and a phase converting unit that acquires phase information from the reception signal, and tracks the object by monitoring a peak BIN, and a phase offset between the peak BIN and another BIN based on the phase information. As the reception signal, the signal processing unit may use micro-vibration data about the object to sense the object. A system including: a transceiving unit that transmits and receives an FMCW radar signal; and the sensor device according to the first aspect of the present invention is provided.