How to distinguish subscription from woocommerce and MailChimp forms

I use the MailChimp for WP plugin. Currently, I have a MailChimp list that can be subscribed from the checkout of woocommerce and a customized MailChimp form.

But when someone subscribes to the list, I cant distinguish whether he comes from the woocommerce checkout or the MailChimp form. I really want to put these subscribers to the same list. Is there a way to distinguish them? like add a flag field for the woocommerce subscription in the MailChimp list or something else. Can someone explain specifically and clearly how to do it?

Thanks.