With the XPression/DashBoard plugin, it's pretty easy (if I understood your request properly).
I have an XPression Take item with a text field:

It is TakeID 61, and the published field is called TITLE.
In DB, I can add my XPression using the following button:

Once you do that, it will appear in your Device Tree:

If you double click on the Sequence Item panel, if you don't have the license for this feature, I think it will tell you so.
Once you have the XP in your tree, in your Custom Panel, you can add it with this button (after you double click anywhere in PanelBuilder mode):

So now, you have access to the XPression's parameters within your panel.
If you use the Params button, and drag and drop a parameter, you will see XPression's parameters in the popup:

If you search for "take61", you will see only the parameters that have to do with take item 61. If you scroll down, you will see the text for the "title" published field.

If you select that, and click OK, it will put that parameter in your panel.

Any change that is made to the text in XPression is immediately shown in the text field in DB. Any change in DB is sent when the text box loses focus. If you want the text box in DB to immediately send any text changes, you can add the "w.immediate" flag, set to true on the parameter view. Just go into panel builder mode, double click on the text box, and add the following:

#DashBoard