You mean the screen lock passcode on the iPhone and the local account password on the Mac? For the iPhone screen lock passcode, sorry, but there is nothing anyone here or at Apple can do to get past that. It is a strictly device local passcode so not available anywhere but in the mind of whomever set it up. The only way to reset it is to erase the device. That’s all Apple could do as well in such a case. And note if you try to guess it 8-10 times in a row it will become disabled anyway and would have to be erased then.
You can contact Apple about what legal information they’d require to reset and release his AppleID to you. If his Mac was set up to reset the account password with his AppleID, having access to his AppleID may allow you to reset that local account password.
But getting access to the Mac may depend on the model and MacOS (does it have a T2 encryption chip? Is it running MacOS Catalina? Is it FileVault locked?). So you’d best call Apple and ask them about if you can get into it, and if so, what legal documentation do they require to assist you with it.
But the iPhone screen lock passcode is simply not something they even can help anyone with. iOS very deliberately has no way to recover it - only reset it by erasing the device.