If Checkbox in form is checked, add specific product to shopping cart automatically

Please can you assist me. I am new to this and new to adding custom code to Wordpress, so all assistance would be greatly appreciated.

I have a checkbox in a form called 'box-1' and when the users ticks this box, i want wordpress to automatically add a specific product to its woocommerce shopping cart (product id: 507).

How would you add this to the backend of wordpress and get the form to make the call to the function/code before submitting the details ?