It’s easy to check in php that curl is installed or not.

<?php
        // ### Checks for presence of the cURL extension.
function _isCurlInstalled() {
	if  (in_array  ('curl', get_loaded_extensions())) {
		return true;
	}
	else{
		return false;
	}
}

if (_isCurlInstalled()){
 echo "cURL is installed";
} else{
 echo "cURL is NOT installed";
}

exit;

?>

How to check curl version in php Click Here