...
    void ViewshedGeoElement::graphic3dMouseClicked()
    {
        qDebug()<<"m_graphic3d";
    }

    bool ViewshedGeoElement::eventFilter(QObject *obj, QEvent *event)
    {
        qDebug()<<obj<<event;
        if (event->type() == QEvent::MouseButtonPress)
        {
            graphic3dMouseClicked();
            return true;
        }
        return false;
    }
...

Esri::ArcGISRuntime::Graphic* m_graphic3d = nullptr;
m_model3d = new ModelSceneSymbol(QUrl(dataPath + PathModel), 1.0f, this);
m_model3d->setAnchorPosition(SceneSymbolAnchorPosition::Bottom);
m_model3d->setHeading(180.0f);
m_graphic3d = new Graphic(dp.m_pos, m_model3d, this);

m_graphic3d->attributes()->insertAttribute(HEADING, dp.m_heading);
m_graphic3d->attributes()->insertAttribute(PITCH, dp.m_pitch);
m_graphic3d->attributes()->insertAttribute(ROLL, dp.m_roll);

m_sceneView->graphicsOverlays()->at(0)->graphics()->installEventFilter(m_graphic3d);
...

...
void ViewshedGeoElement::graphic3dMouseClicked()
{
    qDebug()<<"m_graphic3d";
}
...
QObject::connect(m_graphic3d,SIGNAL(mousePressEvent()),this,SLOT(graphic3dMouseClicked()));