I know that insects and geckos are able to do this because of clinging pads, or something like that, but they have a very low weight limit so therefore would not be able to support a human. So how else could a human climb like said gecko and/or insect?
It would require bio-engineering
Impossible with existing human biology
On a perfectly smooth vertical wand, the science based answer will be no. A human being cannot cause enough friction, certainly not with its existing, biological means. No Vanderwaals force will keep you safely on the wand. I agree with AlexP's comment in the opening: a tool is needed for this.
Even if you would stick..
Suppose there would be some sticking substance. A genetic modification to climb walls like spiders do would be difficult to handle for humans, because we don't have 6-8 attachment points, only 2.. and human hands have a relatively small area to stick on the wand.. The sticking would need to carry the weight. It could be too strong, the human would not be able to detach the hand from the wand and proceed upward.
Feet are not handy for this
We are bipedal animals, our feet and knees have adjusted to move forward. Human feet cannot be used to help climb a vertical wall, even if they would stick. When using the feet or toes to stick and move upward, your center of gravity moves off the wall.. which will require more sticking force. Or.. gravity will break a limb.
How to solve the issue..
Some sticking could be introduced on the side of the feet. But any solution would involve very strong arms, in the first place.. same time, make the "sticking" controllable: suppose the human hand could strengthen or weaken the sticking force, at will.. changing a chemical compound by sweating.. or use a non-chemical method: change the shape of the hand, to allow some kind of Magdenburger hemispheres.. but these changes would require bio-engineering !