invite
聘 centers on formally inviting someone, especially for an official role or visit. The core idea is a respectful summons or invitation.
聘 combines 耳 (ear) with 甹, which likely contributes the sound and relates to inquiry or summoning. The exact historical development of 甹 is uncertain, but the character is associated with formal invitations.
The left side is an ear 耳, and the right side 甹 looks like a formal document being presented. Imagine someone listening carefully as they receive a written invitation.
For ヘイ, picture a formal invitation arriving on a tray: the tray is held out and you say 'Hey!' in surprise. Hey -> ヘイ, and the invitation is extended to you.