Assign Domain Name on a IP:PORT Listener

On one of my Droplets, I have a Java Socket Listener at Port :5000. Something like:

ServerSocket serverSocket = new ServerSocket(5000);
Socket socket = serverSocket.accept();

And since there is an Public IP Address on my Droplet, i am able to listen at (example):

123.123.123.123:5000

It is fine. But now, how do i make my Domain Name to be applied on top of IP Address please. I mean, to be like:

www.example.com:5000

I have my DNS already pointing to Server. But I don’t know how to apply (or) bind it to a Port like that. Is it about NGINX? Or can it be done with Apache too? (Because i have Apache also running inside for Web Server) But how do i achieve that please?

Please kindly help.