How to point same post url to different page based on source

Hi!

I am wondering how some people make two different post of same url.
When I click on their link from their facebook post, it shows me another post but when I enter the url directly on browser it shows me another post.
In Facebook they are redirecting URL to main wp site using pen.io

Is there anyone know how to do it?

I am looking forward to hearing from someone…!