How to redirect mobile users from my XHMTL site to my WP mobile clone site?

So I have a site which is made in XHMTL.
I simply need some mobile detection code that will redirect visitors to my mobile optimized WP site.

i.e. visitor comes to my site via their Android: https://www.mysite.com
code redirects them to: https://www.mysite.com/m

I’m sure its been discuss a billion times (I couldn’t find it amidst the sea of posts here.

Thanks in advance!