Someone と Anyone
SomeoneとAnyone。ごっちゃになりやすいですが、どちらかの意味を覚えていれば大丈夫です。
Someone
特定の誰か1人
Example:
Someone is in my house.
Did someone drink my milk?
Anyone
誰でも、ひとりでも複数でも可(any person or any people)
Example:
I haven't seen anyone.
Does anyone have milk?
参考
Cambridge Dictionary | English Dictionary, Translations & Thesaurus