a field at the product where the customer can type a text

[nick@bodoni.nl]

Hello all,
I would put by the product a textfield where the customer can type text. (some words)
This text must be at that product list so I know what that text is.
I want to sel QR code stickers and the customer must be type a link or something else, than I know what to make.

How do I do that?
I have VM 2.0.18a
thanks Nick