Most laptop mics are condenser electret mics which usually use a small dc current, although not always.

Not the last time I went down this road hardening a Thinkpad, see Step 6 at [1] (not my site). I haven't bothered with any smartphones yet, so I can't speak to what they tend to use for a mic. But if I carried one I'd definitely rip out all the voice coils and rely on a pair of headphones w/integrated mic for voice comms to mitigate potential for eavesdropping.

[1] https://blog.patternsinthevoid.net/replacing-a-thinkpad-x60-...

When replacing the lightning assembly on my iPhone 6, I noticed that the microphone looks passive. Here’s a photo[0]; It’s the little bronze(?) square next to the headphone jack.

[0]: https://www.ifixit.com/Store/iPhone/iPhone-6-Lightning-Conne...