Yes, you can use CTA generared by Hubspot platform but with a small change.
This is the typical CTA code:

<!--HubSpot Call-to-Action Code -->
<span class="hs-cta-wrapper" id="hs-cta-wrapper">
    <span class="hs-cta-node hs-cta" id="hs-cta">
        <!--[if lte IE 8]><div id="hs-cta-ie-element"></div><![endif]-->
        <a href="http://cta-redirect.hubspot.com/cta/redirect/99999/unique"><img class="hs-cta-img" id="hs-cta-img-unique" style="border-width:0px;" src="https://no-cache.hubspot.com/cta/default/9999/unique.png" /></a>
    </span>
    <script charset="utf-8" src="https://js.hscta.net/cta/current.js"></script>
    <script type="text/javascript">
        hbspt.cta.load(99999, 'unique-id');
    </script>
</span>
<!-- end HubSpot Call-to-Action Code -->

Valid code for Omniconvert Creatives:

<!--HubSpot Call-to-Action Code -->
<span class="hs-cta-wrapper" id="hs-cta-wrapper">
    <span class="hs-cta-node hs-cta" id="hs-cta">
        <!--[if lte IE 8]><div id="hs-cta-ie-element"></div><![endif]-->
        <a href="http://cta-redirect.hubspot.com/cta/redirect/99999/unique"><img class="hs-cta-img" id="hs-cta-img-unique" style="border-width:0px;" src="https://no-cache.hubspot.com/cta/default/9999/unique.png" /></a>
    </span>
    <script charset="utf-8" src="https://js.hscta.net/cta/current.js"></script>
    <script type="text/javascript">
        setTimeout(function() { hbspt.cta.load(99999, 'unique-id'); },2000);
    </script>
</span>
<!-- end HubSpot Call-to-Action Code -->

This small change is necessary because our creative code is loaded on demand and we must wait for hubspot javascript to be loaded before.
If you have already included http://js.hscta.net/cta/current.js in your website code before our creative is loaded, this change is not necessary.