To measure the room conditions we can use a traditional Thermo-Hygrometer as shown in the image.
If you want to see these conditions from any location around your home then you can use a cheap DHTxx shield connected to a D1 mini and dweet its data to dweet.io. Use freeboard.io to make these data visible at any location. The program sample dht_dweet.lua can be downloaded from Sourceforge.
You can use your smartphone or a tablet to visualize the room conditions of the observed room (https://freeboard.io/board/BQK578).