I am sharing my method to index backlinks. I never knew this method is available.
It's not like fast link indexers. This is manual method. We need to insert each link everytime.
Method
Step 1: Go to - https://search.google.com/test/mobile-friendly
Step 2: Insert URL & Run Test. Once the page is Analayzed. We have the option "Submit to Google".
Step 3: Click on "Submit to Google" to index backlink in Google.
Sometimes Google will index backlinks fast, sometimes it will take time.
Note: This works only for mobile optimized sites. Most of the web 2.0 sites are mobile optimized only.
I hope you like.