Your Pentium 2020M is Socket G2 / rPGA988B
First of all, you show a 2nd generation desktop CPU. I don't have to look that up. Of course it won't fit, and wouldn't work if it did. Laptop CPUs are specialty repair items.
http://www.cpu-world.com/CPUs/Pentium_Dual-Core/Intel-Pentium%20Mobile%202020M.html
You also have to match the core logic.
And, there could be a bios list in the laptop of what CPU's would be recognized.
No laptop brand supports cpu or graphics upgrading.
In order to upgrade the combined CPU/Graphics,
1) CPU Package has to match.
2) Motherboard Core logic (often called chipset, though it is only one chip now) has to be compatible.
3) The CPU needs to be recognized by the Bios. Now, that is only known by Lenovo. If there's an i3 or i5 5940 machine type it may have a common bios. If you find a Lenovo model with the same motherboard, you can use that system bios. Bios is the software on a motherboard IC that runs before the Registry and Windows on the HDD.
4) The power level needs to be acceptable. The Pentium is 35 watts maximum. 45 or 55 watt i7's may not get the power from the motherboard or could overheat.
5) You need to find one on ebay or other source. Laptops are not build-your-own. The parts are not commonly available except to replace broken ones.
6) It is a complex process taking apart a laptop and changing the cpu with new thermal paste after cleaning the heat sink, and then putting it back together without damage. Only experienced people completely disassemble a laptop and put it back together again.
Typically, people say you can't do it. I worked for IBM and Lenovo for 31 years in engineering. It can sometimes be done, but it is a challenge and accomplishment to boast about if you successfully upgrade a cpu.
Forget about the desktop/tower ones. You need M suffix cpus for that laptop. It may be i3-3xxxM, i3-4xxxM, i5-3xxxM, i5-4xxxM, depending on what fits #1,2,3,4 rules above.