Update box with combo box

This is quite simple I know, but I only get my hands on Access whenever I
need it so I’m always forgetting simple tasks like this one. I even had some
trouble choosing this question’s title, can you imagine it? :/

I have two tables, ORDERS and PRODUCTS.

My ORDERS form has a combo box where I can pick the PRODUCT code from the
PRODUCTS table but I also want to see the PRODUCT_NAME (PRODUCTS table) field
on this form in a different box.

Thx in advance.