The basic gist of this trick is that you can set up your iPhone to always be in a “listening” state. From there, you can have the audio picked up by your iPhone and transmitted right back to your AirPods. Note that this iPhone trick also works with regular AirPods, Powerbeats, and AirPods Max.
Admittedly, it’s only natural to view this iPhone hack in the context of listening in on other peoples’ conversations. Still, it’s worth bringing to your attention as something of a safety warning. Specifically, if you see a random iPhone just laying around, don’t assume it’s safe to talk about sensitive information.