I have not seen this particular combination before, but without actual quantitative data, it would be hard to call this mixed methods. The alternative are either multi-methods or multiple methods.

Hi Mohammad Kandi , I absolutely second David L Morgan 's. But there are some good examples out there to quantify qualitative data which might serve as starting points for you, e.g.,

https://methodos.hypotheses.org/1795

https://measuringu.com/quantify-qualitative/

https://www.uniteforsight.org/global-health-university/quantify-research

Preferably, you do the analyses differently, then combine them during your discussion section of the research. In the discussion section, the result from in-depth interviews can either support or negate (refute) the content analysis.