Yes. Any person, including a believer, can have an evil spirit in their body and/or their soul, which is the mind, emotions & will of a person. However, the "spirit" of every human being is reserved exclusively for God to come into & dwell in.
Jesus said, "that which is born of the Spirit is [human] spirit..." [John 3:6] showing that when a person is born again [John 3:7] it is the person's own "spirit" that is birthed by God's Spirit.
But, even a Spirit-filled believer can still have enemy spirits that are influencing & even attached to their body (like cancer or some other physical affliction) or influencing or attached to their mind, emotions or will, hindering advancement in Christ.
Importantly, the Greek word in the New Testament for our English translation of "demon-possessed" has the actual definition as being "demonized". So, whether a person has an evil mindset or is completely taken over by demons who control that person's "will" [Mark 5:1] , then according to Scripture that person is "demonized".
[ Book / 2005 - "The Eyes Have It" / Rob C. / 22
Chapters for Ministers who thirst to cast out
demons, lay hands on others with healings and miracles following their ministry and to "have
their senses trained to discern good and evil"
as Hebrews 5:14 instructs. ]