Scrum says nothing about how to track where backlog items come from. In fact, relatively little is said in the Scrum Guide as to what information should be included in a Product Backlog Item and how that information should be formatted. A Product Backlog Item is required to have a description, an ordering, an estimate, and a measure of value.
I've never used the Visual Studio project management tools, but nearly every other issue tracker that I've used allows for a textual description of the issue and you can put metadata about the source in there. Some tools allow for "commenting" on issues, and that might be suitable since it's still tracked, but not as in-your-face as the description. Others allow you to customize the fields and you can add people or events associated with a given backlog item.
I would wonder if this is necessary. If this information isn't necessary, it is wasteful to gather, store, and deal with it for every ticket. Although relatively easy to do, if it doesn't add value to you or your customers or allow you to meet some kind of contractual or legal obligation, you shouldn't be doing it.