When you open the camera and point it at the QR code, there's a button that appears to the right. Touch that, and you get the option to Share, Copy link, Add to Reading List, or Open in Safari when pointed at a QR code for a URL. If it's not for a URL, it should just give you the options for Copy and Share.
Select copy and you should be able to paste it in your Notes app or wherever you'd like. Does that work?