Foot clearance above ground is a key factor for a better understanding of the complicated relationship between falls and gait. This paper proposes a wearable system using UWB transceivers to monitor the vertical heel/toe clearance during walking. First, a pair of very small and light antennas is placed on a point approximating to the heel/toe of the foot, acting as a transmitter and receiver. Then, the reflected signal from ground is captured and propagation delay is detected using noise suppressed Modified-Phase-Only-Correlator (MPOC). The performance of the UWB-based system was compared with an ultrasound system for stationary movements. The experimental results show that an overall mean difference between these two systems is about 0.634mm with correlation coefficient value of 0.9604. The UWB-based system is then used to measure foot clearance during walking which shows promising results for gait events detection.