Well, if the issue is that you have no work experience, then that’s what you need.
Have you considered applying to temp positions? Part or full time. There are staffing companies that focus on specific industries, so you might not find an engineering job, but you could find a comp sci or IT support position. Just to get your foot on the door and get some work experience while also pulling a paycheck.
Many people I know have gotten onto the ladder this way, myself included.
Are others complaining to you about his behavior? Because you’re his boss, I wonder if this could function like any other improvement conversation.
What if, instead of calling him “annoying,” you pulled him aside separately at another time and phrased the convo as wanting him to focus on “professionalism” and/or “work appropriate behavior”? If you are clear about what that means and bring examples to the table, that might help.
You could cover his passive aggressive responses in the conversation as well–pointing and writing notes and pity-partying are not appropriate ways to communicate in your workplace.