Haris Zulfiqar

WordPress tooltip plugins lets you add tooltips to plain text and links on your post and pages.
It offers a tinyMCE shortcode GUI which will guide you through the entire process of a tooltip.
This plugin uses jQuery tipTip authored by Drew Wilson http://code.drewwilson.com/entry/tiptip-jquery-plugin.
You can also add tooltips manually by following the pattern below:
<pre><code>[tooltip content="This will show in a tooltip" url="This will make tooltip a link"]Hover over me for tooltip[/tooltip]
</code></pre>
Url is optional. If URL is added, it will render a link otherwise it will be a plain text.

WordPress Tooltip

WordPress tooltip lets you add tooltips to content on your posts and pages.

Toile de Maître

An extension to make accessible tooltips easily using the awesome TippyJS library (https://atomiks.github.io/tippyjs/). 
Works with Gutenberg and classic editor.

Accessible Tooltips

An extension to make accessible tooltips easily using the awesome TippyJS library (https://atomiks.github.io/tippyjs/).

WordPress Tooltip vs Accessible Tooltips