I've run into this really annoying issue when trying to connect to my AirPods. I found out the culprit was from the continuity camera trying to connect every single time a bluetooth device tried to pair.
According to Apple, the continuity camera lets you "Use the powerful camera system of your iPhone to do things never before possible with a webcam, including Center Stage, Portrait mode, Studio Light, and Desk View." It's great – I've used it for video calls before and it has waaay better quality than anything you'd get on a Mac.
But it comes with the most annoying notification and ding or ping noise that can make you go crazy. Here's how to fix it:
Fix The iPhone Continuity Camera Automatically Connecting & Making Noise
If you see this screen, you'll hear the noise. To fix it go to Settings -> AirPlay & HandOff -> and Turn off
Continuity Camera. That's it. You'll never hear the noise again. Hope this helped!