sudo apt-get update
sudo apt-get install -y software-properties-common python-software-properties
sudo add-apt-repository -y \
    ppa:jonathonf/python-3.6 \
    ppa:alex-p/tesseract-ocr
sudo apt-get update
sudo apt-get install -y \
    ghostscript \
    libexempi3 \
    libffi6 \
    pngquant \
    python3.6 \
    qpdf \
    tesseract-ocr \
    unpaper

Source: Installing OCRmyPDF — ocrmypdf 11.5.0.post13+g46d0632 documentation