First of all, there is no foolproof way of protecting anything against a professional hacker. The purpose of VPN's vary. but plays an important role in protecting your privacy. A good VPN will be able to protect you from unnecessary spying on your privacy or unlocking many blocked sites. But many of the free VPN's that are provided does not really ensure this. Their means of revenue are shady. They might sell your information. Therefore it is necessary to use a good paid VPN for any purposes. And to answer your question simply, Yes a hacker can still track even after using a VPN (if its not a good one).
If you using internet you are exposed . nothing fully safe
vpn said as safe but actually not , the vpn provider always logs your actions and activities
but VPN prioritizes open access without censorship thats it
about exploits i will not discuss it here anymore
but as long as you are trying to avoid internet censorship than VPN are usefull
but nothing is safe which is connected to internet
VPN could be more safe if they provide DNS level security otherwise in todays world other vpn services those can not provide dns level security are worst and, waste of money etc
note that only few vpn providers able to offer DNS level protection cause of almost every vpn provider has no IPv6 security
and about can hacker track you even you are behind vpn shield the answer is yes
assume you are visiting a website , your browser loads various scripts , dom elements to show you pages , videos thats it
you dont know or realize what these things do , a simple js scripts can also collect all your system information...
