by doublesharp on WordPress.org
The Validated Field add-on for Advanced Custom Fields provides input masking and server-side validation of other field types.

Example configuration for input masking and regular expression checking of a telephone number field.
The Validated Field add-on for Advanced Custom Fields
provides a wrapper for other input types which allows you to provide client side input masking using the jQuery
Masked Input Plugin, server side validation using either PHP regular expressions
or PHP code, the option of ensuring a field’s uniqueness for all posts by post_type and meta_key, post_type, or site wide, or a
single post by meta_key, as well as marking a field as read-only. Edit your fields in the ACF Field Group editor and update code using the ACE.js
IDE with autocomplete and syntax validation.
Requires Advanced Custom Fields version 4.0 or greater.