Can a msg box be populated via a macro variable?

I have a macro that produces a value and the value is assigned to a variable i.e. myvar. Myvar does not exist on any sheet, and the value it contains exists only as a consequence of the actions of the macro. I want to display the value of myvar in a text box on a form. Do I first have to put that value in a cell on a sheet and point the text box at that cell, or can I pass that value directly to the text box? If it is possible to circumvent the need to put the value in a cell on a sheet how would I do that please.

Many thanks for your interest and help.