How do I clean microphone and speaker on iPhone x

A stiff brush, like a clean (brand new out of the box) toothbrush is also helpful. Make sure the grate is pointing down when you brush so things fall out rather than in.

You can clean them with a cotton swab or combine a soft pick with a microfiber cloth. Do not use compressed air or a metal tool

Try using a toothbrush? Lightly brush the speaker as not to damage the speaker.