Go to Facebook Business Manager
If you aren't already using Facebook Business manager, you will need to set up a new Business Manager account in order to share your Facebook Pixel
Go to Business Manager Settings
Go to your Business Manager Settings in the left hand menu.
Go to Pixels
Next, navigate to "Pixels" under "Data Sources" in the left hand menu.
Assign the Partner
Select the Pixel and click "Assign Partners".
Enter the Partner's Business ID
To grant you access to the pixel, you need to enter your partner's Business ID.
Once you've done this, your partner should now have access to your Facebook pixel.