You can see who sent the widget in two places: in the analytics of the widget and in “Contacts” > “Segments”.
Open the widget, then the “Analytics” section.
You’ll see the analytics for the widget and all the people it was shown to. If you want to see only those who clicked on the “Send” button, click on the link “Clicked on the button/link” in the second-left rectangle at the top of the screen.
Clicking on a visitor will take you to their card.
You can build a segment of people who viewed or sent the widget. To do this, go to “Contacts” > “Segments” and click on “Add segment”.
In the opened window, specify the conditions “Web form … submitted” and “Characteristics: email present”. So you build a segment of people who sent the widget and typed their email address in the input field. That is, those whose contact details you have collected using the widget.