Here's how you can verify the mobile number registered with your Aadhaar online, according to the UIDAI website:
Go to the UIDAI website, find and click on the 'Verify Email/Mobile Number' link.
On the next page, fill in the Aadhaar number, mobile number and security code in the given fields as specified. After this, click on the 'Get One Time Password' link.

You will receive your Aadhaar mobile verification code in an SMS. This password is sent to the number registered with Aadhaar.
Enter the password received on your mobile in the OTP field.
Click on the 'Verify OTP' button to proceed.
For valid entries, the next page displays the message: "Congratulation!
The Mobile Number matches with our records!"

(At the end of the verification, the UIDAI portal displays the result of the same in the form of a message)
Mobile number not registered with Aadhaar?
"Registered Mobile Number is essential to avail Aadhaar Online services," according to the UIDAI.
In case your mobile number is not registered with your Aadhaar, visit the nearest Permanent Aadhaar Centre (PAC), it adds.