How do I get love emoji into the mini golf king game?

You can scroll through the Emojis. You can only use the ones in the game. It's the three dots on the bottom left side. Come join our team.. Brooks Clan

As first Guest answered, to add to it you can only use the emojis they offer. Hearts on equipment only means it is their favourite(s) for easier and faster selection during a match per time limit. To do that you have to go to main lobby where you select a stage to play and click on the golf icon at the bottom left to see equipment according to grouping, you can favorite only those you have unlocked.