Hey @ersin !
This is indeed possible, though does require a bit of code in the binding / wherever you intend to use this data.
Basically, within custom JS I would recommend either setting the value to state by putting:
state.whatever = context.builderContent.data.whatever
Or, in your data binding you can access directly with
context.builderContent.data.whatever
I think there is a world where we eventually add the ability for a custom field to be added to state as a flag on the field itself, but for now this is the best practice route.
If you think that is a use case you will use a lot, I recommend submitting a feature request to our ideas board at ideas.builder.io !
Hope this helps !