I no longer have a Facebook account,... So therefore their is clearly some tracking going on based on my device profile, IP address or some other data they are able to slurp without my knowledge to track what I have been looking at on the internet.
Having no FB account doesn't stop them ILLEGALLY profiling them. To start with, they won't have deleted anything when you deleted your account - your data is too valuable to them for them ever delete anything !
It is clear (look up some of the details in the Max Schrems case) that they keep a very detailed profile on people - and if you think about it, some of it isn't hard to do. One of the things they do is to nag users to "just upload your contacts so we can invite them" - and people are daft enough to do it (also illegal). Say one person uploads you home phone/email and another uploads your work details - FB can now tie your personal and work details together.
But the online tracking is also intrusive, pervasive, and sneaky. Ever noticed all those sites with a little "f" logo on them ? When those icons, as well as doing something related to FB, hide tracking code that allows FB to harvest a lot of information about your browsing habits. Very similar approach to the tracking Google does via it's tracking code disguised as statistics gathering for the site owner.