I made a project using Phalcon for a customer. I couldn't convince customer to install Phalcon as extension. Is there a similar framework to migrate project easily?
That kinda depends on how you set up your project. Are you using events, listeners, and dependency injection extensively? If so, you might need to look at a Symphony/Doctrine2 combo or perhaps Zend Framework 2/Doctrine2. I came to Phalcon from ZF2, and the transition is not extremely drastic. Having said that, if you have a complicated project that uses things like Phalcon's Form implementation, you will have quite a bit of work ahead of you regardless. If the app is a very vanilla MVC app, you might be in better luck, but it will still be painful.
Good luck with a conversion. It would have been nice is the customer had indicated ahead of time that they wouldn't change their PHP configuration!
I really don't know if it helps for you, but there is a php written version of Phalcon available on https://phalconpi.com.