At the moment when someone uploads a photo of you onto Facebook, the only way you will know about it is if they tag you or if someone else tells you about it. However that could change in the future as Facebook has announced that they will begin using facial recognition to notify users when photos of them are uploaded onto the social network.
However there is a catch and that is these users will have to agree to allow Facebook to keep a facial template on file. This might raise some eyebrows due to privacy concerns, but if you’re particularly concerned about having your photos uploaded and shared on Facebook without your permission, that will have to be a small price to pay.
Note that this feature is completely optional so users can choose to not bother with it if they’d rather not have Facebook keep their facial templates on file. That being said, this feature seems to be only available in the US for now due to the different privacy laws in other regions. This feature also seems to be similar to how Facebook announced that they would combat revenge porn.
This also involved users uploading photo(s) of the image they think might be uploaded by a vengeful ex so that Facebook can preempt it before the photo even gets posted. There was some controversy with this solution that Facebook has attempted to address.