Let's see how someone can easily create a CF7 form with 3 horizontal fields (Name, Email, Submit) in the same line and integrate MailChimp mailing lists.
Create a new CF7 with the fields below:
<div class="grve-one-third">[text* your-name placeholder "YOUR NAME"]</div> <div class="grve-one-third">[text* your-name placeholder "YOUR EMAIL"]</div> <div class="grve-one-third grve-last-column">[submit "Send your message"]</div>
Then, you can use the Contact Form 7 Mailchimp Extension https://wordpress.org/plugins/contact-form-7-mailchimp-extension/ in order to use your mailchimp account.