Checkbox in product template to add another product

Hello,

I am using the Shop App and I would like to be able to add extra products (not variants) from the product page. So for example if I am selling a bike, I would like a checkbox to also add a bikelock on the product page, so when checkbox is checked I add to cart > A bike and a lock will be added to the cart. What would be the best solution for this?

Thanks, Mike