Info regarding contact form

Hi everyone

I am after some help please (-:

I am using WP 4.0 and have 1 contact form on my contact page which works fine, I am also have created a new form where I want the user to enter the form details and when they click ‘add to cart’ the info the customer entered automatically gets added to the cart and checkout page?

I have see this work on another website but not sure if its another plugin or something else?

I really appreciate it if someone could help me with this as I have been scratching my head and googling for days!!

Thanks in advance
Simon