How to add third party tracking code on Marketo Landing paegs

Hi Team,

We have created Landing page on Marketo and added embed code for form. before submitting the forms we want to add third party tracking code like we have CTA named "Download" on forms on-click or on forms submission we want to executive that code how we can achieve it.

For Ex. onclick download CTA - tracking code (in Javascript) is - xyz('track', 'DownloadNow');