DOCPROPERTY and DOCVARIABLE fields simply reflect the stored values. It is not a two way process.
Thinking laterally, you could use a text content control to display the value e.g. lets assume you have a content control with its name and property tag set as 'Name' and you have a docVariable called 'varName' containing a default name. By using the On enter and on exit events for the content control you can fill the control with the value from the variable and if you change the content, the variable will be updated with the change.
A Custom (or built-in) DocProperty would work in a similar manner to the docvariable, as also shown for the custom property PropNum and the content control tagged "Number". The code goes in the ThisDocument module of the document. Note that not all built-in document properties are editable.
You might find http://www.gmayor.com/BookmarkandVariableEditor.htm useful if only to create the initial variables/docproperties.
Option Explicit
Private Sub Document_ContentControlOnEnter(ByVal ContentControl As ContentControl)
Select Case ContentControl.Tag
Case Is = "Name"
ContentControl.Range.Text = ActiveDocument.Variables("varName").Value
Case Is = "Number"
ContentControl.Range.Text = ActiveDocument.CustomDocumentProperties("PropNum").Value
Case Else
End Select
End Sub
Private Sub Document_ContentControlOnExit(ByVal ContentControl As ContentControl, Cancel As Boolean)
Select Case ContentControl.Tag
Case Is = "Name"
If ContentControl.ShowingPlaceholderText = False Then
If Not ActiveDocument.Variables("varName").Value = ContentControl.Range.Text Then
ActiveDocument.Variables("varName").Value = ContentControl.Range.Text
End If
End If
Case Is = "Number"
If ContentControl.ShowingPlaceholderText = False Then
If Not ActiveDocument.CustomDocumentProperties("PropNum").Value = ContentControl.Range.Text Then
ActiveDocument.CustomDocumentProperties("PropNum").Value = ContentControl.Range.Text
End If
End If
Case Else
End Select
End Sub
In practice, you would probably want to write the variable value to the control using the document open event or in the case of a template, the document new event.