Selected Answer
Hello tcarnahan and welcome to the forum,
This can be easily achieved with a Worksheet_BeforeDoubleClick event. The following is what I used in a project some years ago:
As mentioned in the code the checkbox cells are formatted with font 'Wingdings2' and "P" inserts a checkmark
Private Sub Worksheet_BeforeDoubleClick(ByVal Target As Range, Cancel As Boolean)
' macro written by WillieD24, Dec. 27/09
' this code will change the cell value to "P" if it is nothing or
' change it to nothing if it is "P"
' the checkbox cells are formatted with font 'Wingdings2' and "P" inserts a checkmark
On Error GoTo Line999 ' exit the sub
' restrict code to a particular column (change A:A to suit)
' if any column other than "A" is selected the code will end
If Intersect(Range("A:A"), Selection) Is Nothing Then Exit Sub
If Target.Value = "P" Then
Target.Value = ""
Else: Target.Value = "P"
End If
Cancel = True
Line999:
End Sub
This code is placed in the worksheet code window.
If this solves your issue then plesae mark my answer as selected.
Cheers :-)