It sounds like you’re after a chat link cable. Search for “Elgato 2GC309904002 Chat Link Cable”, they’re about $10, so not going to be amazing quality but will work just fine.
The diagram on this UK store shows how it works: https://www.argos.co.uk/product/7350739
Amazon link https://www.amazon.com/dp/B017F85Q0S/
I’m guessing you’re not intending on creating your own but if you are, they are fairly straightforward to wire up, the only tough bit is squeezing two decent cables into a mini jack and finding somewhere to ‘hide’ two 10k resistors( needed to prevent the output loading).
Hi Mikey, to solve this issue I use an Elgato Chat Link - Party Chat Adapter for Xbox One and PlayStation 4. It allowed me to catcher the game chat. I added the link to the one I bought from Amazon. you will also need an aux cord with with 4pole-Conductor. I use the TRRS 3.5mm Audio Cable which I also bought from Amazon, I was a 2 pack. It’s the second link. It costed me only $16.98 before tax. $9.99 and $6.99.
2 Pack TRRS 3.5mm Audio Cable,... https://www.amazon.com/dp/B07PJW6RQ7?ref=ppx_pop_mob_ap_share