Ninja Forms use email from form for email_from and email_from_name.

ninja_forms_change_from_address.php

add_action( 'ninja_forms_email_admin', 'ninja_forms_change_from_address' );
function ninja_forms_change_from_address(){
   global $ninja_forms_processing;
   if( 1 == $ninja_forms_processing->get_form_ID() ) {
	$user_email = $ninja_forms_processing->get_field_value( 2 );
	$user_name = $ninja_forms_processing->get_field_value( 1 );
	$ninja_forms_processing->update_form_setting( 'email_from', $user_email );
	$ninja_forms_processing->update_form_setting( 'email_from_name', $user_name );
   }
}