How People Turn iPhones into Bluetooth Bugs

With iOS 12, Apple added a feature, called Live Listen, which essentially turns your AirPods into on-demand hearing aids. 

There's a bit of setup you'll need to do, but once it's done, you can place your phone on a table closer to the person you're talking to and it will send audio to your AirPods.

On your iPhone go to Settings > Control Center > Customize Controls and tap on the green "+" symbol next to the Hearing option. Then, when you need to use the feature put in your AirPods and open Control Center on your iPhone and select the Hearing icon followed by Live Listen. Turn off the feature by repeating those final steps in Control Center. more

Corporate Espionage Alert: If a person excuses themselves from a business meeting to go to the restroom (or other excuse)... NEVER continue the discussion thinking they won't know. They may be using this trick to listen in to what you are saying. More sage corporate counterespionage advice here.