1\ Article 92 of the General Principles of the Civil Law of People's Republic of China (PRC) stipulates that if improper benefits are obtained and losses are caused to others, the improper benefits obtained shall be returned to the person who has suffered losses; According to Article 270 of the Criminal Law of People's Republic of China (PRC), it is a crime of embezzlement to illegally possess other people's property and refuse to return it in a large amount. Whoever illegally takes another person's forgetting things or buried objects for himself and refuses to hand them over in a large amount shall also be treated as embezzlement.
2\ So you have the right to ask him to return your mobile phone, and if he refuses to return it, he can be investigated for criminal responsibility;