How can I tell what is triggering Bluetooth in use icon on my menubar

I have enabled the Bluetooth menu bar item in System Preferences. Now, whenever a device is trying to talk to my Mac (or vice versa, I suppose) I will see the Bluetooth icon with 3-dots through it.

Question:

How can I tell what device is triggering this activity?

Solution 1:

Now, whenever a device is trying to talk to my Mac (or vice versa, I suppose) I will see the Bluetooth icon with 3-dots through it.

That's not what it means.

The icon means that Bluetooth is enabled and at least one device is connected.

From the Apple Support Document, Using a Bluetooth mouse, keyboard or trackpad with your Mac:

If you want to see what device is connected, just open the Bluetooth drop down menu. Whatever is in bold is what's connected.