How to get Universal Links iOS (not my App)?

I hope someone can help me out here as I didn't find anything in the internet about it.

I want to open ios apps from my website, for this I have to use the universal links from this app. But where I can find it? For example: If a user clicks on the Facebook link it should open the FB app if installed or forward to App Store. I know the old was (custom URI scheme) was fb:// but this should be used anymore.

Thanks in advance,