Exploit targets with ncat as metasploit over wan targets

Hello world!

I am learning about ethical hacking (I dont like it) for a subjects in my college. We are learning about exploits and payloads. Exploits tool such as metasploit. Nevertheless, I’m not confortable with the quality of this framework. I’m learning about ncat and I found him more flexible. But I dont know how to use it to open shells and gain root acess over wan targets or web server.

Does anybody knows how to use use ncat to set exploit and payloads like it was acting as metasploit framework? How to use ncat with ngrok as well to use it outside wan? Please give me some examples.