You can use amphp/react-adapter + amphp/amp, which will give you an ev based implementation – if ev is installed – that is fully compatible with ReactPHP's LoopInterface.
$driver = (new Amp\Loop\DriverFactory)->create();
$loop = new Amp\ReactAdapter\ReactAdapter($driver);
// $loop is now a ReactPHP compatible driver based on ext-evIf you don't want the automatic driver selection based on the available extensions, you can also instantiate a driver on your own using $driver = new Amp\Loop\EvDriver;.