It isn't very easy to do this but if you have KDE it will be a little easier.
First, Open Terminal and type the following command:
sudo apt install kubuntu-desktop
Once it is done installing, go to https://www.emojipedia.org/apple in your webbrowser. Screenshot each one of those emojis. Open the screenshots with gimp and transparent the background.
Now, open system settings and click on the tab that says icons. It will put you in icon settings. In icon settings there will be two tabs. One will say Icons, and one will say Emoticons. Click the one that says Emoticons. A little plus sign will be on the bottom left corner. Click it. It will ask for the name of the theme so put Apple. Then it will ask you to select the theme of emoticons you want to create so click KDE Emoticons Theme.
Now, click the tab that says Apple. There will be a plus sign on the bottom left corner and one in the middle click the one in the middle. Add all the screenshots you took and type what you want to activate them.
Then, select Apple as your default emoji theme.
When you toggle emoticon list, the apple emojis will be there instead of the google emojis.
Only do this if you really care about having apple emojis on ubuntu because it is pretty hard to screenshot each one of the emojis and transparent the backgrounds.