How to redirect and submit a form on a WP woocommerce site?

Question

JavaScript

Good day!
WP online store on Woo, you need to make sure that after filling in the data about the buyer in the basket section - when you click the "Checkout" button, the data is sent to the mail and a redirect occurs to another site.
Previously, on other (not on WP) tasks, I did it through here such code

$(document).ready(function () {
  //----------------------Отправка формы-------------------------
  $("#кнопка").submit(function (e) {
    e.preventDefault();
    var th = $(this);
    $.ajax({
      type: "POST",
      url: somePHP, // php обработчик формы
      data: th.serialize(),
    }).done(function () {
      
    });
  });
 
});

Now I'm trying to do the same through the "Custom CSS & JS" plugin, but it doesn't work.
Perhaps there are some other plugins or ways
Thank you in advance for your answer