Q: Iphone 6 when make a call , people can't hear me .why?

Try to reset your device. This won't delete your data stored on this device.

• Press and hold the Sleep/Wake button
• Press and hold on the Home button
• Keep holding both buttons until the display turns off and back on with Apple logo on it.

Alternatively, you may go to Settings - General - Reset - Reset All Settings

Then take a look at this article, maybe it will help you If you can't hear a person on a call or voicemail or if the sound isn't clear on your iPhone - Apple Support