Thanks to Jason McCreary
https://jason.pureconcepts.net/2012/10/install-pear-pecl-mac-os-x/
$ sudo pecl install mongodb
NB: Take a note the path, for me :/usr/local/Cellar/php71/7.1.13_24/lib/php/extensions/no-debug-non-zts-20160303/mongodb.so
Thanks to Budi Irawan
http://budiirawan.com/install-php-intl-extension-os-x/
- Check php.ini location
$ php --ini
- Add the following line at the bottom of php.ini
extension=/usr/local/Cellar/php71/7.1.13_24/lib/php/extensions/no-debug-non-zts-20160303/mongodb.so