Hi abby_yy,
Thanks for using Apple Support Communities! I see you're having an issue with your iPhone's microphones, and I'd like to help.
Have you restarted your iPhone since noticing this happening? If not, go ahead and restart, as it can resolve unusual issues.
If you have a case on your iPhone, remove it and test if that was the issue.
If not, take a look at this article for steps to follow: If the microphones on your iPhone, iPad, and iPod touch aren't working
Since you also have an issue hearing people while on a call, check out these articles:
If you can't hear a person on a call or voicemail or if the sound isn't clear on your iPhone
If you hear no sound or distorted sound from your iPhone, iPad, or iPod touch speaker
If you need to have your iPhone serviced, this page can help: iPhone Repair and Service
Take care!