Connection from mac mini 4 to 2015 imac retina

Hi,

Your iMac 2015 is not supported as external display, Target Display Mode.

Use your iMac as a display with target display mode – Apple Support (AU)

Eccles49 wrote:

If I buy the mac mini 4 what cables would I need to connect using the imac as a monitor.

If you buy a M4 Mac mini, then you will also need an external display.

see > Connect a display to Mac mini - Apple Support