Haha this is the 3rd or 4th thread I've posted this response in the past few days - very common question it seems. The following is my technique:
Super simple, I actually just posted this in another thread about a case study on Google indexing hacks I've used since they removed the ADDURL tool...
USING OTHER GOOGLE TOOLS
Run the URL of your backlink thru Google PageSpeed Insights
Run the URL of your backlink thru Google Mobile Friendly Test
Run the URL of your backlink thru Google Structured Data Testing Tool
Any of the above should index your link rather quickly or...
USING YOUR OWN WEBSITE + SEARCH CONSOLE
Add the URL you want indexed somewhere in a blog post on a site you have connected to Google Search Console. Submit the blog post URL to Google using the Fetch tool. Once fetched and the status is marked “Complete”, simply click the “Request Indexing” button.
Remember to check the option marked “Crawl this URL and its direct links” so Google follows the link on your page back to the URL you actually want indexed.
THIS WORKS IN MINUTES:
Or if you're using Wordpress, use a redirect plugin like Pretty Links to create a 301 redirect. Create a redirect link like:
yourdomain.com/backlinkurltobeindexed - make sure this link redirects to the backlink URL you want Google to index.
Take that redirect URL you created and again fetch it via Search Console - this method gets my links indexed in 10 min flat
Again, remember to check the option marked “Crawl this URL and its direct links” so Google follows the link on your page back to the URL you actually want indexed.
You can index those redirect URL's in your own search console as if they were your own