If you keep different versions of PHP-FPM you can use different phalcon module on every one. I've used php5 and php7 on the same macbook in the past.
But I suggest you to use docker or a virtual machine to do it. It's easier and cleaner and you'll never come back
I just want to install a new version. But I can't install new version because, I have old version. How delete old version and install new version 3.2. ?