This will also work, entered directly into the ckeditor:
~~START_HTML_BLOCK~~
<code>
<img class="media imap" src="https://mturner.org/userfiles/planets.gif" usemap="#planetmap" /><br />
<map name="planetmap"><area alt="Sun" coords="0,0,82,126" href="https://mturner.org" shape="rect" /><br />
<area alt="Mercury" coords="90,58,3" href="https://dokuwiki.org" shape="circle" /><br />
<area alt="Venus" coords="124,58,8" href="https://www.wikipedia.org/" shape="circle" /></map>
</code>
~~CLOSE_HTML_BLOCK~~
But read the plugin page referenced above for htmlok and htmlblock settings.