On opening the app, the screen shows headings "Orientation" and "Coordinates". Hold the phone by its bottom edge, and tilt it into landscape mode, with the screen facing towards your left hand side.
Credit for the original mod goes to Ruu. Additional contributions by Pespiri. Blame for issues goes to me. Updated for Beat Saber 1.13.4 This release requires BSIPA4, BeatSaberMarkupLanguage (BSML) ...