All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
Even if we presume that the cap which you referred to in the question is worn by the Jews, it is permissible for Muslims to wear it as it is not something peculiar to them that is not worn by others [people of other religions]. Moreover, it might be that the number of Muslims who wear it outnumber the number of Jews who do so.
The criterion of imitation, as stated by the scholars is for a person to do what is absolutely particular and peculiar to another person [or people], and indeed we clarified in Fatwa 84622 that the imitation which we are forbidden from is in things which are peculiar to the people of the Book. Wearing the cap which you referred to in the question is not something that is peculiar to the people of the Book.
Allaah Knows best.