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You didn't give very long for anyone to answer - bumping after 7 minutes is a bit impatient!
I doubt you can check the mobile number. Why would you be able to? These are internet connections, so they'll know the IP address of the device that connects but that's nothing to do with the mobile number (especially if someone uses WiFi). In fact I would think it would be a massive privacy fail if Google or Facebook got your mobile number when you connected to their services. And remember that people can use a browser rather than an app to connect to these things, and that there are different apps which can do this, so even if one app did this there is no reason for the person you suspect to use that.
You can set Facebook to notify you if there is a connection from a browser it does not recognise, so you might do that. Otherwise if you are suspicious that someone is accessing your accounts the best advice I can give is to change you passwords, and enable two-factor authorisation if they support it (not an expert on FB myself, so don't know whether they do).