Cannot choose QtQuick version in Ubuntu

[riffraff]

I have installed qt in Ubuntu. Here are some details about the Ubuntu and QT installation:

$ lsb_release  -a
LSB Version:	core-9.20170808ubuntu1-noarch:security-9.20170808ubuntu1-noarch
Distributor ID:	Ubuntu
Description:	Ubuntu 18.04.6 LTS
Release:	18.04
Codename:	bionic

$ aptitude versions qml-module-qtquick2
Package qml-module-qtquick2:                              
p   5.9.5-0ubuntu1                                              bionic                                   500 
i   5.9.5-0ubuntu1.1                                            bionic-updates                           500 

Package qml-module-qtquick2:i386:
p   5.9.5-0ubuntu1                                              bionic                                   500 
p   5.9.5-0ubuntu1.1                                            bionic-updates                           500

$ qmake --version
QMake version 3.1
Using Qt version 5.9.5 in /usr/lib/x86_64-linux-gnu

I am building the application successfully, without any error or warning, from terminal command line:

$ qmake
$ make

In this application, I need the QtQuick version 2.15. However, if I import it in the main.qml...

import QtQuick 2.15

... I get this runtime error when I start the application:

09:30:29,030 Warning: QQmlApplicationEngine failed to load component
09:30:32,164 Warning: qrc:/main.qml:1 module "QtQuick" version 2.15 is not installed

I can start it only if I import lower QtQuick versions (e.g. 2.9).

Note 1: in the same machine, I have also installed Qt using the installer qt-unified-linux-x64-4.1.1-online.run downloaded from https://www.qt.io/download. If I build the same application and run it with the debugger, with the GUI of qtcreator, I don't have this problem: the QtQuick 2.15 is successfully imported.

Note2: when I install the qtquick...

sudo apt-get install qml-module-qtquick-controls2

It installs the version 5.9.5, which doesn't include the QtQuick 2.15.

What should I do to install properly the qt library, in order that I can import the QtQuick 2.15 in the main.qml when starting the program with the command line?

How can I force the "apt-get install" to install a newer version than 5.9.5?