No. People can not take from your phone. However something to note. Your phone (if its not a phone, dont worry, people still cant nick from you) should have a feature to set it as 'visible to all' or 'invisible' If you have it set to 'invisible' no one will be able to detect your phone anyway. You can change this later if you want it to be visible to someone. What people can do if it is visible is try to send you something. However you have to accept the connection for you to receive it. However I recommend you accept nothing if you dont know who its from by Bluetooth because you never know, someone might try to send you a malicious programme or virus.