Set X-WP-Nonce header

I am trying to load some dynamic value and add it to mail using wpcf7_mail_components filter but I noticed that X-WP-Nonce header is missing from XHR request which leads to empty user object:

object(WP_User)#110 (7) {
  ["data"]    => object(stdClass)#109 (0) {}
  ["ID"]      => int(0)
  ["caps"]    => array(0) {}
  ["cap_key"] => NULL
  ["roles"]   => array(0) {}
  ["allcaps"] => array(0) {}
  ["filter"]  => NULL
}