Sorry for your loss, hopefully it was not too large an amount of btc. If you search that unknown address on a blockchain explorer like blockchain.com, then you can see maybe where the money is going, like for example to an exchange. However, beyond knowing where it goes, sadly you won't be able to get any money back unless the perpetrator is incredibly stupid and cashes out from that address (even then it is unlikely to lead to any justice). Wish you all the best, make sure you do a full scan with an antivirus program on your computer/device so this does not happen again.