I have a report where I use values from a dataset in the header. I just use an expression rather than code at the report level to access the data.
I have a dataset named TopOfPage which returns one row of data though it could return multiple rows because I am just going to reference the first row.
I have a textbox in the page header with the following expression:
Another scenario could be if you have a textbox in the body, let's call it Textbox1. You could reference that through an expression in the page header.
I don't know if either of those will help you out. If not, maybe you could provide more information about what type of object/data you are trying to access in the body to display in the header. If you are unfamiliar with expressions, I could reply with more information about expressions.