I lost my contacts in my iPhone 6 (iOS 9.01). Is it possible to get them from my MacBook pro Retina 13? How?

It is possible to sync contacts from a Mac to an iPhone via iCloud by turning Apple menu > System Preferences > iCloud > Contacts to on in the Mac and by turning Settings > iCloud > Contacts to on in the iPhone.

Before you do that, in particular because I don't know exactly how you "lost" the contacts on the iPhone, be sure to have a backup of the Mac contacts (and you may also want to open the Contacts app on the Mac and do a File menu > Export > Contacts Archive).

The following may also have some information that will help: Get help using iCloud Contacts - Apple Support