TMZ just obtained this 911 call from the Montgomery County Sheriff in Maryland. Nicholas Roske made the initial call, but hung up, and when the operator called him back, he said ... "I'm having thoughts. I've been having them for a long time. I'm from California. I came over here to act on them."

He then said he'd just flown there, took a taxi to Kavanaugh's home and admitted he had a gun with him ... which was unloaded and locked in a case inside his black suitcase.

Roske sounded extremely concerned about his own mental health, telling the operator he wasn't on drugs or alcohol, but said he needs "psychiatric help."

After copping to also having pepper spray and a knife in his luggage, he offers to step further away from the suitcase before police arrive. Roske said, "I want to be fully compliant. So, whatever they want me to do, I'll do."

After they arrested Roske, cops say he told them he was upset about the leaked Supreme Court opinion to overturn Roe v. Wade, as well as the mass shooting in Uvalde, TX. As it turns out, abortion rights protesters were also marching Wednesday outside Kavanaugh's house.

As we reported, the 26-year-old was booked for attempted murder. He told the operator he'd been hospitalized multiple times and has had suicidal thoughts, and that he'd located Justice Kavanaugh's home through an Internet search and cross-referencing a photo of the house.