My 2014 rMBP are main working machine and im trying to mirror to iMac 2013 due to bigger screen but failed.
Both OS are mojave.
Cable used: Mini Display Thunderbolt (rMBP) to HDMI (iMac)
After i plug the cable there's nothing inside my Display, system preference.
Tried Screen sharing but it's too lag for working.

Any other solution?
Thanks in advance.

err... the HDMI is *not* an input.
the cable you bought is for using your rMBP with a TV or projector ... not with an iMac.

dang
has any recommended for my solution?

its not about cable actually, it depends on the Mac hardware.
If your iMac is 21-inch, display input is not supported at all by the hardware
if 27-inch, refer to this page for more info...
https://support.apple.com/en-my/guide/mac-help/mh30822/mac

do check the OS version right at the beginning of the page

I recall TargetDisplay mode works on older MacOS too. Not limited to 10.13-10.15. So long the iMac are the right model that is.

yea, I've used it on 10.9 (Mavericks) worked great

duh...just found out my cable are only capable to screen on TV not imac.
Imac need another specific cable...