Conventional light detection and ranging (LiDAR) systems usually employ equal interval multi-pulses as signal carrier. It leads to error-prone ranging and high false alarm probability. As an unequal interval multi-pulses communication method, pulse position modulation (PPM) can also provide commendable ranging performance for LiDAR. In this letter, a novel integrated sensing and communication optical wireless (ISAC-OW) scheme based on fourth-order PPM (4-PPM) is proposed. And a prototype is demonstrated under laboratory conditions, which can transmit 10 Mbps data while ensuring a ranging accuracy of less than 0.12 millimeters.