The iMac 2024 (M4, 16 GB, 512 GB, Apple M4 10-Core) cannot be used directly as a monitor for a MacBook as it does not support Target Display Mode. This mode is only available on older iMac models (between 2009 and mid-2014) that use macOS High Sierra or earlier.

However, there are alternative methods to use an iMac as an external monitor:

1. AirPlay: Newer iMac models from 2019 onwards support AirPlay, which makes it possible to wirelessly display the screen of another Mac on the iMac. However, both devices must be on the same Wi-Fi network and use macOS Monterey or newer.

2. third-party software: Programmes such as Duet Display or Luna Display offer a way to use an iMac as an external monitor, even if it does not support Target Display Mode. However, these solutions require installation on both devices and may have some limitations.

Overall, using a modern iMac as a monitor for a MacBook is not possible without special software or hardware.