Here is the part you need for your system MacBook Pro 13" Retina (Early 2015) Trackpad Cable, Apple P/N 821-00184-A
I love Apples confusion in the way they manage their parts ID’s! Most companies keep the base P/N and then append a version ID. In your case that would to the letter A or other incrementing value.
But No Apple doesn’t do that! They just spin a new part number! So now which is the newest and which is the older version of the part?? Here’s all of the P/N’s for your cable.
923-01376, 923-00518, 821-00721 & 821-00184
Now the roman way would be to start on the left and make each version to the right be the newer (canonical order), Or if you where in China & Japan then the list would be in the reverse! The most left would be the newest! (non-canonical order) So confusing!
And that assumes the list is in the correct order what if its just any which way! The second being the newest or was it the third??
So any one of these should work! But don’t ask me which is the newest version ;-{