Dynamic from an other page

Hello everybody so here’s my question :
I want to have a dynamic checkbox so when a user clicked the “send” button on my form, the checkbox is checked (so i know that i have received a mail with the form informations). The problem being that my “send” button is on another page so i can’t find this particular button in dynamic options of the checkbox.
Help !

You won’t be able to do that with the button in another page.

You will have to update your dB when the user clicked the send button so that when he/she reached the other page … the checkbox can conditionally change