it need custom code to create repeatable fields but if you want ready-made solution than you may try this : https://github.com/WebDevStudios/CMB2
just include it in your theme/plugin and than check it’s example-functions.php file , it have example of repeatable fields 🙂
here is direct documentation link : http://cmb2.io/docs/field-types#-types-group
it also support many other fields .
Cheers !