We are using Contact Form 7 plugin for this theme, It’s one of the best contact form plugin for WordPress.
You can use default form that comes after installing this plugin or you can use or customize form like the demo.
Go to the Contact > Add New. Here you will see a default form code like the screenshot bellow.
Replace the form code by the code bellow, it will make the form like you demo.
Finally it will look like the screenshot bellow –
Save the form, and go to the contact page and edit the contact page. Here in the visual composer you will see the contact form element. Edit the element in the form select dropdown select the form that you created few minute before.