Install MongoDB + phpMongoDriver in Mac OSX High Sierra

brew install mongodb

First, you have to install mongodb.

nopsled@smleeo3o:~/dump (=｀ω´=)$ php -v PHP 7.1.7 (cli) (built: Jul 15 2017 18:08:09) ( NTS ) Copyright (c) 1997-2017 The PHP Group Zend Engine v3.1.0, Copyright (c) 1998-2017 Zend Technologies

Second, check your php version. this example's php version is 7.1.

brew tap kyslik/php  brew install php71-mongodb

Third, we have to install php MongoDriver 7.1

nopsled@smleeo3o:~ (=｀ω´=)$ cd /usr/local/Cellar/php71-mongodb/1.4.0 nopsled@smleeo3o:/usr/local/Cellar/php71-mongodb/1.4.0 (=｀ω´=)$ ls INSTALL_RECEIPT.json  mongodb.so* nopsled@smleeo3o:/usr/local/Cellar/php71-mongodb/1.4.0 (=｀ω´=)$ cp /etc/php.ini.default /etc/php.ini

Check mongodb.so file and copy your /etc/php.ini.default to /etc/php.ini.

878 ; ... or with a path:  879 ;  880 ;   extension=/path/to/extension/msql.so  881 ;  882     extension=/usr/local/Cellar/php71-mongodb/1.4.0/mongodb.so  883 ; If you only provide the name of the extension, PHP will look for it in its  884 ; default extension directory.  885 ;  886 ; Windows Extensions

And you have to add mognodb.so files location in /etc/php.ini.

nopsled@smleeo3o:/usr/local/Cellar/php71-mongodb/1.4.0 (=｀ω´=)$ sudo apachectl restart

restart your apache.