$ sudo apt-get update
$ sudo apt-get install dh-ocaml 

dh-ocaml is installed in your system.

Make ensure the dh-ocaml package were installed using the commands given below,

$ sudo dpkg-query -l | grep dh-ocaml *

You will get with dh-ocaml package name, version, architecture and description in a table

dh-ocaml package basic information: