A portable electronic device includes a base segment, a sliding segment, and an input module. The base segment defines more than one indicator. The sliding segment is slidably connected to the base segment and defines a pointer operable to align with an indicator. The input module includes a first magnet, a second magnet, and a sensor. The first magnet is received in the base segment. The second magnet is fixed to the sliding segment to align with the first magnet, and is configured for applying a magnetic force to the first magnet. The sensor is connected to the first magnet to sense the magnetic force and convert the magnetic force into a corresponding electrical signal. The electrical signal is inputted to the electronic device.