Insert third party PHP function in Yii2?

Question

Yii

Valar Morghulis!
I ran into such a problem that it was necessary to insert other feedback forms on the site, which I used to do in PHP, but now, on Yii2, I simply have no idea how this is done. I googled and modal windows go everywhere (I did this, everything works great), but so that from the product page itself you can fill in contact information and send it to the mail - it’s unrealistic for me now
Maybe there is some code that will indicate yii2 what is used here pure php where i can insert my feedback form?
again:
Now - order button - a modal window with the product appears - click order again - goes to the ordering page (name, phone, mail ...)
Need - feedback on the product page (them, phone, mail ...)
Help me out!

Answer 1

Do you have this "pure PHP" straight all the way or is it somehow written in the form of functions? If not, then it's better to somehow arrange it in the form of functions, and make a helper out of them. And to pull this helper where it is required.
upd. Well, this is the simplest and most correct (as far as possible) solution if you do not want to design it as a separate component.