How can i measure Distance From Camera to Object using mono Camera?

basically i want calculate distance from camera to Object After Recogniation Object.

We develop a assistance System when we recognize object also tell the user how much far the object.

I know it is possible using stereo camera but it is quite expensive and high computation system are require .

Can it is possible i connected two different Webcam or Ipwebcam with Matlab ?

The thesis also explain some solution.but difficul to implement .

https://zone.biblio.laurentian.ca/bitstream/10219/2458/1/Peyman%20Alizadeh%20MSc.%20Thesis%20Corrected_2_2.pdf