Select the cells (any rows or columns) and run this macro:
Sub commentset()
Dim r As Range
Dim s As String
s = ""
For Each r In Selection
s = s & r.Value
Next
With Range("K9")
.AddComment
.Comment.Visible = False
.Comment.Text Text:=s
End With
End Sub
I picked K9 as the destination to hold the comment, you can pick anything
you want.