If you work for a decent size organisation with even a vague understanding of data protection it's HIGHLY unlikely a member of staff from a different department can access your HR file, unless his role is HR or IT based.
HR systems are built with levels of access precisely to protect data. I'm a senior manager in a large organisation. I can only see the HR accounts of my direct reports, and even then some info is restricted to HR only.
The chances of him being able to access your file are minimal. The chances of him then randomly and deliberately putting your personal number as his forwarding number are miniscule.
There's absolutely no reason anyone would. Phoning you to perv breathe at you? Possible. Forward you all his calls? WHY?
A typo is the most logical explanation.
Either way, IT can see who accessed your file. Raise it with HR, using a SAR if necessary.
Don't make any accusations until the investigation has been completed. It's most likely you're wrong, and if you've told others that he has/might have accessed your record and breached data protection and he hasn't, you could find yourself in the shit. If someone started an allegation like that about me that was unfounded I'd be raising a grievance immediately.
Which is what you should do if he has accessed your data.