I usually pass values in Access, but Excel should be very similar:

How I call the Function:

'goes and gets the Attorney Signature, based on the Short Case Caption
value
strFSAttorneySig = FSAttorneySig(strtxtShortCaseCaption)

'My function which will return  a value to my calling location for me to
use
Public Function FSAttorneySig(strShortCaseCaption As String) As String

.... Code steps - loops through my record set gathering all pertinent
attorney signature information ....

'passes the value back  to the calling location
FSAttorneySig = strFSAttorneySig
End Function


In my example, I am using the strtxtShortCaseCaption to narrow the
results of my call so, I am passing information into my Public Function
as well as passing information back out of my function to the original
procedure.