jhana is simple, it is just absorption, happily absorption, like when you totally concentrate on something like playing your favorite game. It is hard bc ppl think its a magic, but the nature of it is simple, calming in happiness. Jhana is just a method to achieve happiness. If you are happy with money, life, woman.. then jhana is similar to that.
The problem with life happiness is that its very hard to get a totally absorption in it, except some thing like sex where the mind is totally absorbed. But even with sex, its hard for continuous sex for hours, or to get absorbed for hours, it will get bored after some time. Maybe love is a better example, bc ppl can be deeply in love for a long time, in the ecstasy of it. In jhana the mind is totally attracted to something like when you love or like smt very much, it is totally absorbed and content with the matter, while it is not limited by the physical condition of the body like sex. And even with life, truly totally loving some one is hard.
Jhana is not hard, but the hard problem is how to get totally absorbed in something like breath for example. And often ppl try to suppress arising matters which make it very hard to happen, bc suppressing creates stress in the mind. The trick of jhana is relax, playful while concentrate. Ppl concentrate with tense, its the opposite of jhana. The stress is unconscious, so its hard to release.
But it is not something magical. According to sutta the magic happens after fourth jhana after the mind is released from the body. Magic can happen with lesser jhana but must be guided to achieve it. That is the official method of Buddhism. For non religious ppl, there are some shortcut like being a medium for the spirits, or using enchantment. One of my relatives suddenly see the world of the dead, she does not train anything but it can happen. I think many ppl in my story used a method like this, allows some spirit to possess your body and they can open the eye. But it is harmful when ppl dont understand the meaning of it.
Often the spirits make you do bad things, and only bad spirits enjoy in these kind of possession. Good spirit like deva enjoy their own life, they dont need human body. Bad spirits, the Buddha calls them the mara realm.