Hi Rupesh,
You can try the SMMI test - Test All.
If the hardware fault is not found, try checking if you can get alternate earphones
If nothing works Factory reset your phone once. Also, make sure your phone is on the latest software version to avoid any software-related bug.
Kindly visit the nearest service center:
https://www.asus.com/in/support/service-center/indiaDue to the lockdown, service centers may not be functional. Kindly call the service center before you visit one.
How to Enter SMMI_TEST (test hardware)
Go to Calculator=>type " .12345+= "
you will be entered to SMMI_TEST