The usage of a commercial 24 GHz frequency-modulated continuous-wave (FMCW) radar sensor to retrieve sound signals is investigated in this article. Thanks to the great phase measurement capabilities of current radar sensors, low-frequency audio signals can be recovered by measuring the vibrations they induce in objects due to their pressure wave nature. To prove the concept, a sound emitted by a speaker is recorded by analysing the small-scale displacement of a reflective surface using a radar sensor originally devised for automotive and UAV applications at the 24 GHz ISM band.