just got a new Laptop with only one 3.5mm audio jack. To use my headset i got an adapter but the microphone won't work.
everytime i try to search online i get the reverse... (1 female to 2 male jack splitters)
Having a single port doesn't mean it will work with a microphone. Many laptops have very cheap 3.5mm ports installed which even though they may say they are dual (input/output) don't always work as such.
To get around this, you are really better off getting a 3.5mm to USB adapter to make it work. They have way less problems, and the cheap adapters for these work quite well. The adapters come in both single plug (input/output) 3.5mm to USB and dual plug (input and output) 3.5mm to USB.