You can have whoever you'd like to be your advisor in an academic misconduct hearing or case at a college or university across the United States. That being said, schools will have certain preclusions on who may serve directly in such a role. At most public colleges and universities, an attorney can serve the role of an advisor throughout the process including at a potential hearing.
At most private colleges and universities, the advisor has to be a member of the school community. That's not always the case, there are exceptions to that were schools do allow an attorney to serve as an advisor in such a capacity or anyone for that matter of the student's choosing, regardless of what your school's allowances or restrictions are in that regard.
You, unfortunately, cannot depend on the school to do the right thing or to be cognizant of the accused student's rights and interest in the process. You also are not necessarily even afforded the basic right of being presumed innocent until proven otherwise. That's why regardless of the school's policy, you should have an experienced attorney advisor in your corner from the start of the process to make sure that your rights are protected and to best prepare you for the path forward.