I do not know where you can purchase the processor in Poland. However, before you purchase any processor for your laptop you MUST make certain that the laptop BIOS supports the processor.
To do this, contact the manufacturer of the laptop and ask them which processors are compatible with THEIR BIOS. Then, you can select from those processors. And, you can only upgrade the processor if the current processor is not soldered to the motherboard.
Read the 2nd paragraph here: https://www.intel.com/content/www/us/en/support/articles/000005682/processors.html Intel® Desktop Processor Upgrade Information
Ok, but did you know that the i7-7920HQ uses a BGA socket and will need to be soldered to the motherboard?
https://ark.intel.com/products/97462/Intel-Core-i7-7920HQ-Processor-8M-Cache-up-to-4_10-GHz Intel® Core™ i7-7920HQ Processor (8M Cache, up to 4.10 GHz) Product Specifications
You will likely be unsuccessful in this venture, even if you can get the i7-7920HQ, which I doubt.