How do I export the image/PDF added to the form

Hello,

I used Adobe Acrobat Pro DC to prepare form, and added an image field on my form.

I came to realize that I can have PDF added to the image field and was brought to the question in title: once I added an image/PDF, how do I export that very information?

To make myself clearer, here is a scenario:

I create and prepare a form, add an image field; the form is sent to be filled by someone else and that person adds a PDF in the image field.

I receive the filled form in PDF and now want to extract/export the added PDF in the image field.

How do I do that?

If it is not possible to extract/export an added image/PDF in the form, then how may I allow a PDF upload in my form?

Thank you.