The course is offered by a French platform, FUN-MOOC.
You can attend Introduction to Functional Programming in OCaml for free (after you sign up for an account).
The course is in English and runs for a few weeks until end of December 2019.
I am interested in learning more about OCaml after programming a few simple applications in ReasonML. Reason is an alternative syntax for OCaml, and I've come to appreciate its type-safety and programming paradigms.